LP gas pipe replacement

[Warrenjo]

I have a 2003 Winnebago Journey with 100,000 miles. The previous owner(s) drove it on winter roads with ice and salt. As a result there is quite a bit of rust under the coach including the black iron LP pipes.

It has developed a leak(s) that I can detect as coming from the pipes and I plan to replace them. It will be quite a task but not impossible as all of the pipes are exposed.

Is there any alternative to replacing the pipes with new black iron pipes? I will have replacements cut to length and threaded because I do not have the necessary dies.

Requesting suggestions!

[MrMark52]

Home-Flex 1/2” or 3/4” IPS plastic piping and fittings will be easier, can be easily fabricated and fittings installed. Get it at Home Depot.

There may be other brands.

Surprised original was black iron - but hard piping much cheaper when mass producing chassis as precut and threaded pieces can be purchased in bulk.

[bigb56]

All my piping underneath is black iron, I though maybe it was required due to possible damage from road debris and blowouts. The only flexible parts are the rubber line coming off the tank going to the regulator, from the reg to the black pipe and the fill and bleed hoses. Its black pipe all the way to the furnace, water heater, fridge and stove with the exception of the short flex connectors at the furnace and stove and there is a length of rubber at the exterior grill hookup.

[jacwjames]

I have black pipe but other then the little bit that comes right off the tank the rest goes up into the area between the chassis rails and is not exposed to road/weather.



My guess black pipe is used for safety.

[Winemaker2]

I have not used the new flexible gas tubing but understand it is very easy to work with provided you have the correct fittings. It can be bent vs needing elbows etc.
Good for home so guessing it would work for MHs.
https://www.homedepot.com/p/HOME-FLE...073945#overlay

[twinboat]

Since they still seem to be using black pipe, at least in 2017, I would think it's a RVIA code requirement.

Got to wonder why.

[shootist]

They used to not allow galvanized, but now do. I honestly think is was just to keep water and gas pipes from being mixed up. And under the coach, exposed, don’t use flex plastic. Take the old pipe to Lowe’s or hd and have them make each piece up the same as you have. You do have to watch the depth of the threads , it changes your tightened length dramatically.

[153stars]

I would just use black pipe. If your going to Ace or big box store. The guys working there probably never ran pipe. After first thread cut ask to test threads, as dies are adjustable on machines .It's never right on the line die holder. Use regular fitting not coupler that come on pipe those are looser fit to bury deeper for strength. I shoot for 2.5-3 turns by hand until tight. That's about same as factory pipe/nipple. Then your lengths will fall the same or close after tightening. If thread is too big a second / re-cut with die tighter won't match a cut on bare pipe. You have to test fresh pipe end. The re-cut with be bigger than next fresh cut.

[MrMark52]

Black iron pipe is cheap and is likely why it is used. But it does rust. Typically only used for conveying fuel gas vapor.

Galvanized pipe resists corrosion and rust but the galvanizing tends to flake internally so as to plug gas orifices. Typically only used for water piping.

I would have to go back and look - but I believe the old Uniform Mechanical Code (which may now be the International Mechanical Code) stipulates where each is to be used.

[Country Road]

My new home is plumbed for propane with galvanized pipe, so galvanized is used for propane.

I would use black pipe on the RV. The first pipes lasted a long time, so you’ll be ok if the new pipes do the same. Furthermore, the galvanized will rust also at the threads. Rigid metal I believe is used because the pipes need to be exposed for safety and also durable if they get hit with road debris.

[153stars]

Copper with flare fittings were common in older TTs I don't know about MHs I haven't messed with older ones that much. But rub through/abrasion and electrolysis were probably an issue. I remember plastic bushings in place through the frame.
If clearance is tight ,harbor freight has offset pipe wrenches. They help when pipes are up against a surface.
I think you will find the job goes better than think once you start. You could cut out old pipe if too tight. Just keep track of cuts for measurements. Plan ahead some 90s can be installed prior just don't bury them you might still need some give for line up as other end gets good and tight. Remember a pipe fitter isn't going bury every 1/2" thread pipe at 300 foot pounds.
I'm not a fitter by trade but have threaded and run at least a mile of threaded pipe by now. Most jobs have been less than 100' at a time tucked in crowded equptment with lots of fittings.

[MrMark52]

Originally Posted by MrMark52

Black iron pipe is cheap and is likely why it is used. But it does rust. Typically only used for conveying fuel gas vapor.

Galvanized pipe resists corrosion and rust but the galvanizing tends to flake internally so as to plug gas orifices. Typically only used for water piping.

I would have to go back and look - but I believe the old Uniform Mechanical Code (which may now be the International Mechanical Code) stipulates where each is to be used.

For the record -

NFPA-54 does allow galvanized piping for fuel gas.

Inspectapedia has confirmed my experience with fuel gas piping systems - zinc flaking of the pipe’s interior CAN lead to plugged orifices in the fuel consuming equipment.
I’ve unplugged more than a few.

Not as bad of an issue as what happens when copper WAS allowed for final connection of natural gas - provided it was not within a wall or inaccessible space and was the final connection between the appliance gas shut-off valve and appliance.

[Country Road]

Originally Posted by MrMark52

For the record -

NFPA-54 does allow galvanized piping for fuel gas.

Inspectapedia has confirmed my experience with fuel gas piping systems - zinc flaking of the pipe’s interior CAN lead to plugged orifices in the fuel consuming equipment.
I’ve unplugged more than a few.

Not as bad of an issue as what happens when copper WAS allowed for final connection of natural gas - provided it was not within a wall or inaccessible space and was the final connection between the appliance gas shut-off valve and appliance.

Just for the record, I called my propane company, who’s been in business for 50+ years, and asked about the galvanized pipe they installed in my home. They guaranteed me that it’s the pipe of choice used by propane companies, unless local codes DEMAND otherwise. They also said that it has to be hot dipped galvanized and needs to meet other criteria.

[Ray,IN]

NFPA 54, chapter 5, sub-paragraph 5.5 covers allowed piping materials for LP plumbing. Nowhere does it mention galvanized pipe.
reference: https://link.nfpa.org/free-access/publications/54/2021 2021 is the latest version of NFPA 54.


If you have galvanized LP piping in your house, obtain a written statement from that installer that they have complied with NFPA 54.